9.1 average in my 2004 f350 CCLB DRW 4x4, 6.0 of course.

i get mixed responses from people, some say it's only a little low, some say it's completely normal being a dually vs SRW, and some say it should be higher, at least 14ish.

here is about 10 fill ups in a row.





personally, i think it's way too low. sometimes i feel like my license plate doesn't lie...lol

 

yeah, I'd say it's pretty low but what kind and size of tires are you running? any lifts? For comparison, my '06 F350 DRW 6.0 that's bone stock, will max out about 16 mpg freeway going 60 and no more. 65 takes it down to 15. Tow my boat and it drops to 12 mph. When I tow the boat with the camper on, it goes down to 10.5, and that camper is at least 5500#.

 

+1 .

 

It looks like you're doing short runs. If you get it up to temp and run the interstate highway for 10 hours @ 62 mph you'll get the best mpg. But if your jumping in the truck and driving 5 miles here, 10 miles there, etc. your mpg will be about what they are.
My 05 DRW 4X4 LB Crew weighing about 9800lbs just running around short trips will do about 10. If I get on the road and run 60mph for hours I can get 14ish. Towing my 12000lb 5er camper (and a second 5x10 trailer with a golf car on it 1300lbs) @ 62mph from NJ to FL and back the whole trip average was 10.6 mpg last.
I noticed my mileage dropped off too a couple years ago from 16 to 13-14 but I blame it on the fuel. The truck runs great.

 

Have you cleaned the egr valve recently? One of the fleet trucks where i work keeps having egr valve issues. I think it's due to high idle time. That truck will go from 15-16mpg to 11-12mpg when the egr valve starts sticking from carbon buildup. It will also lag and smoke black fairly heavily when you take off after idling for a while. Once you give the egr valve a good cleaning, it's back to running well and good fuel economy. The truck is a bone stock f350 SRW.

My 2wd 2006 f250 6.0 would not get more than 16-16.5mpg at highway speeds unloaded when stock. I got a sct x4 and loaded a mildly more powerful, custom tow tune. The tune kept the egr valve shut at all times. My mpg went up to 19+mpg highway. I then loaded gearhead's srl+ tune onto the truck and got 20-21mph highway. Gearhead tuning also keeps the egr valve shut.

Weak injectors, dirty air filter, low tire psi, and/or low fuel pressure will also hurt fuel economy

 

I have a 2005 DRW 4 wheel drive and get about the same as t_dub.

 

That's worse mileage than I was getting when I had a 2008 F450 pickup with 4.88 gearing. When towing a 50' trailer with two cars in it. I'd say something is up.

 

Making sure the EGR valve is a great suggestion.

A few other things to look for:
1. Tire pressure - maximize it to the safe maximum pressure. Maintain tires in good condition.
2. Check regularly for boost air leaks and check the filter minder to ensure you are not driving w/ a restricted air filter.
3. Verify sensor accuracy. Verify that EBP, MAP, and Baro are all within 0.5 psi of each other at KOEO. Verify that IAT1, IAT2, TFT, EOT, and ECT are within a degree or two of each other after an extended "cold soak" period (12 hours wit engine off).
4. Make sure your brakes aren't dragging

 

Just about summed it up right here......

I don't have a DRW but with my stock size tires im getting about 18-19mpg

 

Kids truck runs around 14 local, pushes 20 highway. Big tires shaved 1 mpg off I swear, but it's his truck, so.......

There are so many variables with these engines and trucks
Tunes
Tires
Fuel additives
Driving habits
Condition of engine
et etc

We are not talking a fleet Taurus, etc where it's apples to apples.

 

Going back to the type of use. If your trips are under 20 miles and no or little highway the engine is never totally heat saturated and it'll never show good mileage. Remember no spark plugs. Heat and compression for ignition. Hotter the better till optimum temp. is reached.

 

Well said Mike! I also saw a 1 mpg loss when I went from all terrain tires to my mud terrains.

 

Wow lots of replies here to read through! I will respond to each post when I get home, I'm currently away from home on my phone.

But to answer 1 question until I get home, it's on 315/75/16 bfg a/t ko2 tires usually filled to 60ish psi all the time.

It seemed to get the same mileage on the stock tires too.

As far as trips, it is 95% short city driving, although most of the time it is warmed up, not sure if that makes a difference. I can't tell you the last time I used the key to start it, every morning I remote start it 10min before I leave, and if I am running in and out of a store or something (10min or less usually) I leave it running via remote start. Maybe all the idle time is causing it to drop a tad too. I'd say on average in 1 day, it idles at least an hour in between trips (not including idle time while at red lights etc)

However like I said, I will read each post later today and respond to each, hopefully all of your suggestions will help me fix my issue and get mileage up even if it's just a few.

 

Everything you wrote in your second paragraph is everything that gives you the worst fuel mileage.
And these are some of the worst conditions for a diesel that needs to work to be efficient. You're always in warm up mode.
. How many hours and how many miles are on your engine?

 

In my opinion, the OP answered his own question on the crappy mileage.